CFD Modeling Study of High Temperature and Low Oxygen Content Exhaust Gases Combustion Furnaces

This paper reports a CFD modeling study on the possibility of using high temperature and low oxygen content exhaust gases as oxidant for combustion in an industrial furnace by a written computer program. Under these conditions,the predicted results for the flow and heat transfer properties are compared with those under the several cases of conventional and highly preheated and diluted air combustion (HPDAC) conditions. Although the calculation procedure is a two dimensional one with the vorticity and stream function as the main hydrodynamic variables; its results can yet be also valid for the three dimensional case. Because of the weakness of the standard or other traditional k-ε models in predicting the spreading rate of axisymmetric jets, and also for the sake of economy and lack of boundary conditions, here the turbulent transport properties are obtained from an algebraic formula. An infinitely single-step chemical reaction (physically controlled) and a model known as “four flux” are considered as combustion and radiation models, respectively. The qualitative and quantitative verification of high temperature and low oxygen content air/exhaust gases combustions and conventional (low and high air temperature) combustions results have been checked and compared, respectively, with those reported in the literature. Finally, in this investigation three modified concepts and new formulas have been proposed and used to define the gas temperature uniformity, the chemical flame size and the maximum flame temperature as the HPDAC’S main unique features achievement criteria.

کلیدواژه ها:

HPDAC ، CFD modeling ، Low oxygen content exhaust gases ، Energy saving ، Thermal-NO